Abstract: In order to provide a welding structure of a tube header and tube stubs which successfully improves the durability thereof against creep and fatigue damage of the tube stubs without interposing a component of a different material between the tube header and the tube stubs, i.e. requiring additional components, a welding structure of the present invention comprises: a tube header (2) being made of ferritic heat resisting steel; a plurality of tube stubs (4) which are welded onto an outer surface of the tube header, each of the tube stubs having a bended section, in which the plurality of tube stubs (4) are made of austenite stainless steel, and welded to the tube header (2) by using nickel base alloy as a welding material.